Re: darcs patch: forkChild, waitForChild, parIO, timeout

Taral wrote:

On 11/8/06, Simon Marlow wrote:

...

Nearly - but this one doesn't nest. Also, it's possible for the Timeout exception to leak.

Okay, nesting could be covered by changing Timeout to Timeout Unique (or something else equivalent). The exception leaking is impossible to avoid so long as the application can catch arbitrary exceptions.

Actually I was mistaken about the leaking exception - I misread the code as having the catchDyn inside the bracket rather than outside. I'm not worried about the programmer being able to catch the Timeout exception, that's just a case of "don't do that". So we have two versions: - Peter Simon's version, which nests but requires an extra thread per timeout and doesn't propagate exceptions from the main thread to the child. - Your version, which doesn't nest but does behave nicely with respect to exceptions delivered from outside. If you can modify your version to nest properly, I think it's a winner. The ideal unique value to use is the ThreadId of the timeout thread. Cheers, Simon